1. Technical Field
In general, aspects of the present invention relate to polysilicon resistor formation. Specifically, aspects of the present invention relate to an implantation approach that, among other things, reduces mask numbers and improves resistor mismatch.
2. Related Art
Polysilicon resistors are commonly utilized in devices such as semiconductor passive devices in various semiconductor applications such as analog-to-digital (ADC) converters, digital-to-analog (DAC) converters, matched resistors, static random access memory (SRAM) device pairings, complimentary metal-oxide semiconductor devices, digital and analog circuits, etc. Among other things, polysilicon resistors are known for their superior linearity. In general, polysilicon resistors can be fabricated on a polysilicon gate material, or by a separate polysilicon deposition process on dielectric oxide or isolation layers. In a typical implementation, the polysilicon resistor is implanted with a dopant over an entire length/width of the resistor surface. Thus, to have multiple resistance values, multiple mask and implant steps are required. Such an approach may lead to reduced performance and manufacturing inefficiencies.